Rare-earth cadmium tellurite chlorides with a structural type exhibiting [Ln₁₂(TeO₃)₁₂] slabs alternating with CdCl ₆ octahedral layers

A series of new rare-earth cadmium metal tellurite chlorides were synthesized by the salt flux technique and characterized by single-crystal X-ray diffraction. The new compounds CdSm₂(TeO₃) ₂Cl₄ (I), CdEu₂(TeO₃) ₂Cl₄ (II), and CdGd₂(TeO₃) ₂Cl₄ (III), adopt layered structures corresponding to sequences of metal oxide [LnTeO₃] and metal halide [Cd _1-xCl₃] layers. They expand the known family of 2D rare-earth selenium oxyhalides into the realm of tellurium(IV) compounds and add a new targeted structure type involving rock salt slabs formed by edge-sharing CdCl₆ octahedra. The major differences in the structures of Se and Te compounds lie in the composition of the cationic slabs {[Ln ₁₁(SeO₃)₁₂]⁹⁺ vs. [Ln ₁₂(TeO₃)₁₂]¹²⁺} and symmetry (orthorhombic for selenites vs. tetragonal for tellurites).